I don't think you need magnification. Maybe reading glasses if your eyes aren't so good. Try using a plane until it won't take a good shaving anymore, then remove the blade and chipbreaker and see if you can find the wear bevel. It should be readily visible, right at the very edge.
You can remove the wear bevel by working the back, but it makes more sense to me to work it from the bevel side. I don't like to do anything to the backs except work them on the finishing stone to remove the burr. You would probably have to go to a coarser stone to remove the wear bevel by working the back, then polish that back out on the finishing stone. Instead, you can work the bevel on your coarse stone, until the edge has moved back far enough that the wear bevel is gone. In other words you are making the blade a tiny bit shorter, until the new edge intersects the unworn portion of the back. Then just refine the scratch pattern to your liking and remove the burr.